When Nadella hosts his first major press conference this week, he's likely to describe - if not officially launch - versions of Word, Excel and PowerPoint designed for Apple Inc's iPad, looking to cash in on a market worth up to $7 billion a year, according to Wall Street analysts.

The technology behind the software is not ground-breaking, but the strategy is: It puts Office at the heart of the company's push to become a leading services company across a variety of platforms - possibly at the expense of Windows and its own Surface tablet.

That perceived willingness to break with the Windows tradition, which remains co-founder Bill Gates' most enduring legacy, has helped spur Microsoft shares to $40-plus levels not seen since the dotcom boom of 2000.